Organometallic precursors as catalyst to grow three-dimensional micro/nanostructures: Spheres, clusters & wires

Abstract

This paper presents the growth and characterization of three-dimensional structures using metal-organic (or organometallic) chemical precursors like M(CH 3) 3 , where M is a metal. Their morphology depends principally on growth temperature and conditions at the surface of the substrate. These 3D structures can be separated into two classes: i) one with (Ga, Al, In) metallic alloys shaped as sphere, sceptre or cylinder and a carbon membrane covering the alloy; ii) the other with semiconductor or oxide nanowires capped by a metallic sphere. The metal-organic precursors can be seen as catalysts molecules that grow semiconductors with micro and nanostructures similar to the role of gold particles used to grow nanowires in the VLS mechanism. We present the MOCVD growth of Ga 2 O 3 , CuGa x O y and (Ga,In)P nanowires using the metal-organic precursors on metallic or metal containing substrates.

CL study of blue and UV emissions in β-Ga2O3 nanowires grown by thermal evaporation of GaN

“…3 shows. Formation of Ga-rich solid spheres at the end of b-Ga 2 O 3 nanowires grown by MOCVD was reported previously by Sacilotti et al 8 The authors suggest that decomposition of the metal-organic precursor used in their synthesis formed Ga spheres, which in turn acted as catalyst in the growth of b-Ga 2 O 3 nanowires. Moreover, the synthesis of b-Ga 2 O 3 nanowires by thermal evaporation of metallic gallium, and their subsequent oxidation has been reported by several authors.…”

“…Particularly, the growth of b-Ga 2 O 3 nanowires has been reported by thermal evaporation, 5 arc-discharge, 6 the hydrothermal method, and metal-organic chemical vapor deposition (MOCVD). 7,8 However, b-Ga 2 O 3 has shown undesired emissions due to the presence of impurities or point defects generated by still unclear mechanisms that must be elucidated. Perhaps the most well-known defect related emission attributed to oxygen vacancies is the blue band centered between 2.6 and 2.9 eV, with a relative peak intensity dependent on the growth method used.…”

(Ga,In)P nanowires grown without intentional catalyst

“…The (Ga,In)P nanowires were grown in a home made MOCVD setup equipped with TEGa ( C1 sccm) as Ga precursor source [4]. The growth temperature (550 À 7501C) and the reactor pressure (70-740 Torr) were the main parameters used in the nanowire growth process, mainly to set the Ga or In content in the (Ga,In)P alloy.…”

“…The pyrolysis of the organometallic molecules produces the Ga metallic that is deposited onto the substrate also helping the growth process [4,5,19,20]. As In and P atoms are initially available in the chamber by the InP evaporation, we cannot discard their eventual participation in the wire nucleation process.…”

“…Metalorganic chemical vapor-phase deposition (MOCVD) is currently one of the most common techniques used to grow nanostructures for research and industrial applications, which includes heterostructures like GaP/GaInP nanowires, optoelectronic devices, solar cells, lasers, and sensors [1][2][3][4][5]. Other growth methods like molecular beam epitaxy have also been largely used [6].…”